Halogen-free and concentration
Medium-voltage cables with increased fire protection with this sheath material fulfil all national and international requirements in accordance with DIN EN 50267-2-1 and IEC 60754.
Smoke density and toxicity
To ensure that escape and rescue routes remain visible in the event of a fire, the smoke density is tested and verified in accordance with IEC 61034-1/2. This value is calculated by measuring the attenuation of light caused by smoke. Furthermore, all requirements regarding toxicity in accordance with DIN EN 50305 are more than fulfilled.
Low flammability, minimal fire spread and self-extinguishing
Fire tests are divided into three separate categories, which differ in terms of the flame impingement time and the required non-metallic volume per meter (fire volume). Here, a standardised ladder is fitted with test specimens until the sum of these test specimens has reached the required fire volume. The test specimens are then exposed to a flame from a burner, whereby the oxygen content and temperature must follow strict requirements.
Once the official flame impingement time is up, the burner is switched off and the flame must extinguish by itself. Only now are the scorch marks and/or fire spread on the cable measured. A test specimen may exhibit scorch marks at a maximum of 2.5 metres above the burner.
Contrary to what may be expected, the successful completion of a specific fire test depends not only on the sheath material, but also on the cable construction elements (e.g. conductor material, filling compound, aluminium foil) and the test specimens fitted to the fire ladder.
Over the past two years, Nexans has implemented an exclusive portfolio of fire tests in this area, making it easier to assess the fire performance of a specific cable design prior to testing.
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Fire tests as per ICE 60332-3
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Category A
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Category B
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Category C*
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Non-metallic volume per meter (l)
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7
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3.5
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1.5
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Flame impingement time (min)
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40
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40
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20
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*Products in accordance with DIN VDE 0276-622 require a fire spread property compared with IEC 60332-3 CAT-C or EN 50266-2-4 Cat. C
Savings potential
Savings potential becomes clear when you take into account the other laying and fire protection measures. The increased mechanical strength does away with the need for protective tubes, and thanks to the outstanding fire properties, expensive fire-resistant coatings for cables in substations or central control rooms are not required. The new fire-proof cables are particularly effective at transition points, such as the final bushing point before a substation, as well as in power plants, underground railways, underground power supply systems or tunnels.
Application examples in the market
Examples of current market applications include the installation of medium-voltage fire-proof cables on the Istanbul Metro, where around 150 km of cables have been installed to ensure safe tunnel cabling.
E.ON Kernkraft is using the new cable with increased fire performance suitable for underground installation to connect a substation in Grafenrheinfeld. This application will benefit from the excellent mechanical properties of the fire-proof cables.
An Austrian transport company is also using this new type of fire-proof cable to update its tunnel systems in line with modern safety and fire protection specifications.
Nexans – ahead of its time
As part of a European initiative to standardise and revise fire protection regulations and the building products directive, Nexans is working with ZVEI and EUROPACABLE to redefine the general conditions. The goal is to establish standardised fire performance classes (EUROCLASSES) that provide explicit information about aspects such as smoke development, corrosiveness and fire spread. As soon as the relevant decisions have been made here, Nexans will assign its fire-proof cable to the various classes.
In the past, PVC-sheathed cables offered something of a compromise of properties.
